This application is based upon and claims the benefit of priority from the prior Japanese Patent Application No. 2000-200210, filed Jul. 9, 2002, the entire contents of which are incorporated herein by reference.
1. Field of the Invention
The present invention relates to a photoconductive switch module, which can be realized by a combination of light-emitting elements and photoconductive switch elements, and more particularly to a small photoconductive switch module in which photoconductive switch elements are integrated.
2. Description of the Related Art
U.S. Pat. No. 6,407,401B1 discloses a small high-frequency/high-performance photoconductive relay. The photoconductive relay, which realizes a small high-frequency switch, includes a photoconductive switch element, whose resistance varies according to the intensity of incident light, and a light-emitting element, which emits light to illuminate the photoconductive switch element, the photoconductive switch element and the light-emitting element being closely positioned to face each other. This photoconductive relay provides a minimum unit of a switch that can take the on state and the off state.
The photoconductive switch element is an important element when realizing a photoconductive relay (photoconductive switch) and, e.g., U.S. Pat. No. 6,252,221B1 discloses an example of such an element.
In order to realize a sophisticated switch module, photoconductive switch elements must be used to constitute a switch circuit.
In order to obtain good high-frequency characteristics, the circuit design must be carried out in such a manner that the layout becomes as compact as possible, i.e., wiring becomes short. That is, the photoconductive switch elements must be arranged in close proximity to each other.
The present invention is, in one aspect, directed to a photoconductive switch module. The photoconductive switch module comprises a first substrate having light-emitting elements, a second substrate having photoconductive switch elements, whose number is equal to that of the light-emitting elements. The light-emitting elements face the photoconductive switch elements so that the photoconductive switch elements are turned on/off in accordance with lighting/extinction of the light-emitting elements. The photoconductive switch module further comprises a third substrate arranged between the first substrate and the second substrate. The third substrate has through holes, whose number is equal to that of the light-emitting elements. Drive light emitted from a light-emitting element is trapped within a through hole to travel to a photoconductive switch element. The first substrate and the third substrate are connected to each other by heating and pressure contacting of first metal members.
The present invention is, in another aspect, directed to a manufacturing method of such a photoconductive switch module. The manufacturing method comprises providing first metal members on a first surface of the third substrate facing the first substrate, and connecting the first substrate with the third substrate by heating and pressure contacting of the first metal members. The manufacturing method, more preferably, further comprises providing second metal members on a second surface of the third substrate facing the second substrate, and connecting the second substrate with the third substrate by heating and pressure contacting of the second metal members.
Advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out hereinafter.